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This is a review and detailed measurements of the Auralic Leo GX "atomic clock" outboard option for the Vega G2 that I just reviewed. It is on kind loan from a member. The LEO GX costs US $8,299.

The LEO GX comes in the same enclosure as the Vega DAC:

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Strangely for a device that just produces a clock pulse for the DAC, the thing goes through a lengthy boot process and "loading applications." Likely it is the same OS as the DAC and is there to manage the display and such.

A one hour count-time timer is shown on the display. The clock source is "oven" controlled and they are waiting for it to reach target temp. The unit works immediately though so you don't have to wait for that.

The back panel shows more connectors than you would expect:

In addition to the coax connector which carries the clock source to the DAC, it also has a required HDMI connector (not to be confused as a real AV HDMI connection). That is there for control as the LEO GX produces the native clock of the DAC based on current sample rate. So it needs to be told that rate. Typically such clocks generate a single frequency that the DAC then divides down to generate the sample clock. Because of that, the LEO GX has two atomic clocks, one at 44.1 kHz and multiples and the other, for 48 kHz and multiples.

DAC Master Clock Audio Measurements
I started with the all important jitter test since that is our main tool for examination of clock quality and jitter:

As noted on the graph, waiting or not made no difference. Nor did the addition of LEO GX clock. Performance remained identical and excellent all around. This is a very high resolution spectrum analysis as you can tell by the tiniest little pulses peaking down at whopping -150 dB. Yet it can't find any difference in the analog output of the DAC -- the thing you listen to -- whatsoever.

Here is our dashboard view, first with the LEO GX clock active:

I think turned off the Master clock as suggested in the menu to compare the two modes and I was greeted with this:

The clock rate was all over the place as were the rest of the numbers. Clearly the DAC had lost its mind, I mean clock source. So much for any ability to compare. It took a reboot with its lengthy period to get functionality back. This is a serious bug as comparing the modes is exactly what you would want to do when you first get this clock.

Listening Tests
I played through a few of my reference files and I was shocked to hear a bit more detail. There was more air between instruments. The bass was ever so slightly quicker. I don't think I have ever heard a DAC sound this good before!

Of course, none of that happened. The DAC sounded just as good as it did yesterday without the external clock. I did not try to time the tracks to see if they finish more on time so maybe they did.

Conclusions
I don't doubt that fair amount of engineering and cost has gone into producing the Auralic Vega GX. As seems to be the trend, designers chase lay intuition of audiophiles and produce products to fill that "need." Audiophile thinks a more accurate sound means more focused soundstage, etc. companies deliver. Psychoacoustics tells us that we are not at all sensitive to rate of playback or no one would have ever listened to analog sources like LP and tape. Variations in clock are important but not its absolute accuracy. So unless you want to tell time from your DAC, you have no need for an "atomic clock."

So please, please don't waste your money on such things. And certainly not for US $8,300. For the thousands of dollars you paid for your Vega G2 DAC, you better get the best clock in the business and not need an external source. And oh, an external source can never be as good as a clock source right next to the DAC. The cable degrades the signal as it travels over a few feet of that. FYI, this unit came with a fancy, thick and pain in the neck to screw and unscrew coax cable.

Major Contributor

Its on the high side, but quite a few pro external clocks cost several thousand dollars. People sing the praises of the sound. Now they have a genuine utility in a studio synching multiple devices. Functional clocks for that purpose can be had for $1500 or less with the ability to clock a large number of devices. And other than synching devices I don't believe any improve sound quality.

"The real purpose of the scientific method is to make sure Nature hasn't misled you into thinking you know something you don't actually know." Robert M. Persig

Member

On the bright side you could install these in geographically disperate data centers to try to coordinate globally unique transaction locks or mount them in the trunk of your autonomous vehicle research mule to synchronize your sensors for your fusion algorithms.

Member

Listening Tests
I played through a few of my reference files and I was shocked to hear a bit more detail. There was more air between instruments. The bass was ever so slightly quicker. I don't think I have ever heard a DAC sound this good before!

Of course, none of that happened. The DAC sounded just as good as it did yesterday without the external clock. I did not try to time the tracks to see if they finish more on time so maybe they did.

Major Contributor

As a newcomer to audio, I still never understood why anyone needs these external clocks. I suppose in studios with multiple DACs or processors, having one clock to unify all the units perhaps somehow? (I'm litterally talking out of my ass, I still have no idea how this would work or even if such a use case exists).

Also, "atomic clock"? The heck? Is that what the LAN port is for, to hook up to the internet and periodically ping the atomic time?

Better yet, what's up with the 0.99419 ...How's that accuracy? Shouldn't it be dead set 1kHz?? Better yet, where is this price coming from if the timing on a "master clock" isn't accurate???

Major Contributor

As a newcomer to audio, I still never understood why anyone needs these external clocks. I suppose in studios with multiple DACs or processors, having one clock to unify all the units perhaps somehow? (I'm litterally talking out of my ass, I still have no idea how this would work or even if such a use case exists).

Major Contributor

As a newcomer to audio, I still never understood why anyone needs these external clocks. I suppose in studios with multiple DACs or processors, having one clock to unify all the units perhaps somehow? (I'm litterally talking out of my ass, I still have no idea how this would work or even if such a use case exists).

Also, "atomic clock"? The heck? Is that what the LAN port is for, to hook up to the internet and periodically ping the atomic time?

Better yet, what's up with the 0.99419 ...How's that accuracy? Shouldn't it be dead set 1kHz?? Better yet, where is this price coming from if the timing on a "master clock" isn't accurate???

They don't ping atomic clocks. They actually (at least some) have an on-board rubidium atomic clock. Yes, in studio use they might have 8 or more clock outputs that can run all over a studio and clock all the various digital devices in synch for recording purposes. You don't need an atomic clock for this, but the more expensive ones have that.

Not a manufacturer, but I assume an atomic clock isn't cheap to make. Regular crystal oscillators are of course fine for audio use. My sub $400 Focusrite 18i20 has a word clock connection that could be used the same way. It uses the inexpensive crystal clock inside for that purpose. Usually the cabling to connect clocks will introduce more jitter than even the inexpensive crystal clocks. So the atomic variety are just like audiophile foolishness only for pro studioes.

"The real purpose of the scientific method is to make sure Nature hasn't misled you into thinking you know something you don't actually know." Robert M. Persig

Senior Member

Master clocks were relevant in complex setups that needed to synchronise audio with video running on separate machines or cope with digital routing between various devices using SPDIF, ADAT, etc. Here is an example of a master clock device made for that purpose:

Member

I really did not expect it to cost more than the DAC. Still struggling with that concept.

On the other hand, it did make the dac more accurate. Went from .99999 to 1.00000, so it is subtle and undetectable to the human hear, but it is an improvement. But that’s paying $14,800 to get equivalent clock performance to the Element-x which nails the clock perfectly at no extra fee and still get SINAD that is not quite as good. But these are the first real measurements of these devices made available to the public, so it was mostly guesswork for the buyer before this. Thanks again, Amir for helping make the audio market a more honest place.

Member

That is a common practice they learned from dCS. Auralic is just a follower as people says dCS Vivaldi sounds great with a clock!

In the digital world, how could you tell my dac is the best as to be honest if they all sound the same? Adding more complexity and price! If you cannot tell the difference, you either not be able to afford or your ear is too bad to hear it.